CN114250334A - Desulfurization slag modifier and molten iron desulfurization method - Google Patents

Desulfurization slag modifier and molten iron desulfurization method Download PDF

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Publication number
CN114250334A
CN114250334A CN202111486012.6A CN202111486012A CN114250334A CN 114250334 A CN114250334 A CN 114250334A CN 202111486012 A CN202111486012 A CN 202111486012A CN 114250334 A CN114250334 A CN 114250334A
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desulfurization
slag
molten iron
modifier
weight
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CN202111486012.6A
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CN114250334B (en
Inventor
周剑丰
齐江华
邓必荣
李明晖
罗钢
梁亮
劳栋
陈杰
苏风光
成志强
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Lysteel Co Ltd
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Lysteel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0037—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 by injecting powdered material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C21C7/0645—Agents used for dephosphorising or desulfurising
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

The invention provides a desulfurization slag modifier and a molten iron desulfurization method, wherein the desulfurization slag modifier comprises the following raw material components in parts by weight based on 100 parts by weight: na (Na)2CO360-75 parts by weight of soda powder with the weight percentage not less than 90 wt%; 15-25 parts of lime powder with the weight percentage of CaO not less than 80 wt%; CaF210-15 parts by weight of fluorite powder with the weight percentage content not less than 80 wt%. When the desulfurization slag modifier provided by the invention is used for desulfurization, a part of front slag can be retained in a ladle, and the desulfurization slag modifier can modify the front slag to improve the desulfurization capability of the front slag, so that the slag skimming time of the front slag is reduced, the excessive cooling of molten iron is avoided, the desulfurization efficiency is effectively improved, and the obvious economic benefit is brought to enterprises.

Description

Desulfurization slag modifier and molten iron desulfurization method
Technical Field
The application relates to the technical field of molten iron pretreatment, in particular to a desulfurization slag modifier and a molten steel desulfurization method.
Background
With the rapid development of science and technology and the steel industry, the requirement of modern industry on the quality of steel is higher and higher, S is a harmful element in steel, the plasticity and toughness of the steel can be reduced, and the steel product is easy to generate hot brittleness. The pretreatment and desulfurization of molten iron are important process means for improving the quality of steel products, expanding the variety of steel products and reducing the cost in the modern steelmaking production. The current common methods for pretreating and desulfurizing molten iron mainly comprise a blowing method and a KR method.
Before KR desulfurization is carried out by using the existing desulfurizer, front slag in a ladle must be completely removed, otherwise, excessive slag is generated after desulfurization, the slag is difficult to remove, and resulfurization occurs during steelmaking, so that the mechanical property of steel is poor. Generally, a long time is consumed for slagging-off before desulfurization, and the temperature of molten iron is seriously reduced, so that the subsequent desulfurization efficiency is reduced, and the economic benefit of iron and steel enterprises is seriously influenced.
Disclosure of Invention
The application provides a desulfurization slag modifier and a molten steel desulfurization method, and aims to solve the problems that the temperature of molten iron is seriously reduced and the desulfurization efficiency of the molten steel is influenced due to overlong slagging-off time before the molten steel desulfurization.
On one hand, the embodiment of the application provides a desulfurization slag modifier, which comprises the following raw material components in parts by weight based on 100 parts by weight: na (Na)2CO3Is heavy60-75 parts by weight of soda powder with the weight percentage content not less than 90 wt%; 15-25 parts of lime powder with the weight percentage of CaO not less than 80 wt%; CaF210-15 parts by weight of fluorite powder with the weight percentage content not less than 80 wt%.
Optionally, the desulfurization slag modifier is a powder mixture with an average particle size of not more than 1 mm.
Optionally, the content of S in the lime powder and the fluorite powder is not higher than 0.1 wt%.
Optionally, the desulfurization rate of the desulfurization slag modifier is 89-94%.
On the other hand, the embodiment of the application provides a molten iron desulphurization method, which comprises the following steps:
(1) adding the desulfurization slag modifier into a foundry ladle, and scraping front slag in the foundry ladle so as to enable the desulfurization modifier to fully react with the front slag;
(2) and stirring the molten iron in the ladle so as to fully desulfurize the molten iron.
Optionally, before the step (1), slag skimming treatment is performed on the pre-slag in the foundry ladle, and 10-15 wt% of the pre-slag is reserved in the foundry ladle.
Optionally, the time for raking the pre-slag in the step (1) is 20-30 s.
Optionally, the stirring time in the step (2) is 9-10 min, and the stirring speed is 90-110 r/min.
Optionally, after desulfurization, the consumption of the desulfurization slag modifier relative to molten iron is 6-10 Kg/T.
Optionally, after the desulfurization, the loss amount of the molten iron is 1.8-2.5%.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention adopts 60-75 parts by weight of Na2CO3The soda powder with the weight percentage content of not less than 90 wt% is used as the main raw material of the desulfurization residue modifier. The soda powder with the content has strong desulfurization capability, can reduce the melting point and viscosity of the desulfurization slag, and can play a role in dephosphorization at the same time. In a molten iron environment of 1300 ℃, Na2CO3Decomposition into Na2O，Na2Reaction of O with S to form Na2And S, realizing desulfurization.
In order to improve the desulfurization effect and alkalinity of the desulfurization slag modifier, 15-25 parts by weight of lime powder with the weight percentage content of CaO not less than 80 wt% is adopted as one of the raw materials of the desulfurization slag modifier. The lime powder with the content not only can desulfurize and dephosphorize, but also desiliconize the product SiO2The CaO in the lime powder is also needed to adjust the basicity in the molten iron. In addition, the lime powder with the content can not only improve the O content in the slag2-Activity of (2) and can also reduce the viscosity of the slag to make the slag contain S2-The speed of diffusion mass transfer from the slag-metal interface to the slag is accelerated, so that the slag desulfurization capability is improved.
The desulfurization residue modifier also comprises 10-15 parts by weight of CaF2Not less than 80 wt% of fluorite powder. The fluorite powder does not have the desulfurization capability, but the content of the fluorite powder can increase O in slag2-The activity of the calcium sulfate can obviously increase the desulfurization speed of the lime powder, and the fluorite powder can also reduce the melting point of the desulfurization slag and improve the fluidity of the desulfurization slag.
When the desulfurization slag modifier provided by the invention is used for desulfurization, the desulfurization effect is good, part of the front slag can be retained in the ladle, and the desulfurization slag modifier can modify the front slag, so that the desulfurization capability of the front slag is improved, the slag skimming time of the front slag is reduced, the excessive cooling of molten iron is avoided, the desulfurization efficiency is effectively improved, and the obvious economic benefit is brought to enterprises.
Detailed Description
In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail with reference to the following embodiments. It should be understood that the embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.
For the sake of brevity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form ranges not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and similarly any upper limit may be combined with any other upper limit to form a range not explicitly recited. Also, although not explicitly recited, each point or individual value between endpoints of a range is encompassed within the range. Thus, each point or individual value can form a range not explicitly recited as its own lower or upper limit in combination with any other point or individual value or in combination with other lower or upper limits.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description more particularly exemplifies illustrative embodiments. At various points throughout this application, guidance is provided through a list of embodiments that can be used in various combinations. In various embodiments, the lists are provided as representative groups and should not be construed as exhaustive.
S is a harmful element in steel, reduces the plasticity and toughness of steel, and easily causes hot embrittlement of steel products. The pretreatment and desulfurization of molten iron are important process means for improving the quality of steel products, expanding the variety of steel products and reducing the cost in the modern steelmaking production.
The KR method is a common desulphurization method for molten iron pretreatment, and specifically comprises the steps of inserting a baked cross-shaped stirring head which is cast with refractory materials into a molten iron tank with a certain amount of molten iron to rotate, so that the molten iron forms a vortex, and then adding a weighed desulfurizer into the rotating molten iron through a vibrating feeder (or a rotary feeder). After entering the molten iron tank, the desulfurizer is quickly involved into the molten iron by vortex and fully reacts with S in the molten iron in the continuous stirring process, thereby achieving the aim of desulfurization. The KR method has the advantages of strong deep desulfurization capability, low equipment cost, short production flow, high treatment capability and the like. Although KR molten iron desulphurization can control the S content of the molten iron to be within a reasonable range, the KR molten iron desulphurization needs to completely remove the pre-slag in the foundry ladle before desulphurization. However, in the actual production operation process, the pre-slag in the ladle is difficult to completely remove, the slag removing time is long, and the temperature of molten iron is seriously reduced, so that the subsequent desulfurization efficiency is directly influenced, and the economic benefit of iron and steel enterprises is seriously influenced.
The desulfurization residue modifier provided by the invention can solve the problems, and is specifically described below by combining with an embodiment.
Desulfurization slag modifier
The embodiment of the first aspect of the invention provides a desulfurization slag modifier, which comprises the following raw material components in parts by weight based on 100 parts by weight: na (Na)2CO360-75 parts by weight of soda powder with the weight percentage not less than 90 wt%; 15-25 parts of lime powder with the weight percentage of CaO not less than 80 wt%; CaF210-15 parts by weight of fluorite powder with the weight percentage content not less than 80 wt%.
According to the embodiment of the invention, Na is added in the molten iron environment of 1300 DEG C2CO3Decomposition into Na2O，Na2Reaction of O with S to form Na2And S, realizing desulfurization. Thereby increasing Na in the slag2O can obviously improve the content of sulfide in the slag and accelerate the desulfurization mass transfer and chemical reaction in the slag phase, thereby improving the thermodynamic and kinetic conditions of the desulfurization reaction of the whole molten pool. Experimental research shows that under the same experimental conditions, 3% of Na is added into the slag2CO3Compared with unmodified slag, the sulfur content in the slag is improved by 121%, the sulfur content in the molten iron is reduced by 50%, the transfer of sulfur elements in the molten iron to the slag is promoted, and the desulfurization efficiency of the molten iron is obviously improved.
Meanwhile, the soda powder has strong desulfurization capability, can reduce the melting point and viscosity of the desulfurization slag, and can also play a role in increasing the alkalinity of the slag. But due to Na2CO3Has certain corrosiveness to refractory materials of a hot metal ladle, so the adding amount of the refractory materials of the hot metal ladle must be controlled within a reasonable range.
In the application, the desulfurization residue modifier accounts for 60-75 parts by weight of soda powder based on 100 parts by weight. For example, soda powder is 60 parts by weight, 62 parts by weight, 65 parts by weight, 68 parts by weight, 70 parts by weight, 72 parts by weight, and 75 parts by weight. The content of soda powder can be any combination range of the above numerical values.
In this application, in order toImprove the desulfurization effect of soda powder, Na in the soda powder2CO3The weight percentage of the component (A) is not less than 90 wt%. For example, Na2CO3In an amount of 90 wt%, 92 wt%, 95 wt% or more.
According to the embodiment of the invention, lime powder is another main raw material of the desulfurization slag modifier. The lime powder not only can remove sulfur and phosphorus, but also can remove silicon to produce SiO2The CaO in the lime powder is also needed to adjust the basicity in the molten iron. In addition, the lime powder can also improve O in slag2-Activity of and reducing viscosity of slag, S in slag2-The speed of diffusion mass transfer from the slag iron interface to the slag is accelerated, so that the slag desulfurization capability is improved. Experimental research shows that the binary basicity (CaO and SiO) of the slag is equal to that of the slag under the same experimental conditions2Ratio) is increased from 0.5 to 2, the sulfur content in the slag is increased by 136.7%, the sulfur content in the molten iron is reduced by 42.7%, the transfer of sulfur element in the molten iron to the slag is promoted, and the desulfurization efficiency of the molten iron is obviously improved.
In the application, the desulfurization residue modifier is 15-25 parts by weight of lime powder based on 100 parts by weight. For example, the lime powder is 15 parts by weight, 17 parts by weight, 19 parts by weight, 20 parts by weight, 22 parts by weight, or 25 parts by weight. The content of the lime powder can be any combination range of the above numerical values.
In the application, in order to improve the slag desulfurization capability, the weight percentage content of CaO in the lime powder is not less than 80 wt%. For example, the weight percent CaO content can be 80, 83, 85, 88, 90, 92, or more.
According to the embodiment of the invention, the fluorite powder does not have the desulfurization capability, but the fluorite powder is mixed into the desulfurization slag modifier, so that the O content in the slag can be increased2-The activity of the method is to accelerate the desulfurization reaction of the slag-iron interface, further promote the transfer of sulfur element to slag, accelerate the migration speed of sulfur element in molten iron and improve the desulfurization efficiency of the molten iron. Meanwhile, the addition of fluorite powder can also reduce the melting point of the desulfurization slag and improve the fluidity of the desulfurization slag. However, the excessive amount of fluorite powder causes a problem of a large amount of liquid phase in the desulfurization residue, so that the desulfurization residue is liable to adhere to the stirringA large slag ring is formed on the device.
In the application, the desulfurization residue modifier is 10-15 parts by weight of fluorite powder based on 100 parts by weight. For example, the fluorite powder is 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, or 15 parts by weight. The content of the lime powder can be any combination range of the above numerical values.
According to the embodiment of the invention, the synergistic effect of soda powder, lime powder and fluorite powder in the desulfurization slag modifier achieves the purpose of increasing Na of slag2The content of O, the alkalinity of the slag, the viscosity of the slag and other comprehensive effects are improved, the sulfur element capacity of the slag is obviously improved, the molten iron desulphurization reaction of a slag-iron interface is promoted, and the molten pool desulphurization effect is improved. When the desulfurization slag modifier provided by the invention is used for desulfurization, the front slag in the ladle does not need to be scraped completely, a part of the front slag can be remained for continuous desulfurization operation, the slag scraping time is short, the temperature reduction of molten iron is small, and the desulfurization efficiency is high, so that the aim of improving the economic benefit of iron and steel enterprises is fulfilled.
In some embodiments, the devulcanized slag modifier is a powder mixture having an average particle size of no greater than 1 mm.
According to the embodiment of the invention, the reaction interface of the desulfurization slag modifier with the average particle size of not more than 1mm is larger, and the reaction efficiency can be effectively improved. For example, the desulfurization residue modifier may have an average particle diameter of 0.8mm, 0.6mm, 0.5mm, 0.3mm or less. At the moment, each raw material component in the desulfurization residue modifier fully plays a respective role, and the desulfurization efficiency is high and the desulfurization effect is good.
In some embodiments, the S content of both the lime powder and the fluorite powder is no greater than 0.1 wt%.
According to the embodiment of the invention, when the S content in the lime powder and the fluorite powder is not higher than 0.1 wt%, the influence on the desulfurization effect is negligible.
In some embodiments, the desulfurization degree of the desulfurization residue modifier is 89-94%.
According to the embodiment of the invention, when the desulfurization rate of the desulfurization slag modifier reaches 89-94% in the molten iron desulfurization stage, the molten iron can enter a steel-making furnace for smelting in the next step, and a steel blank with good mechanical property and surface quality can be obtained.
Preparation of desulfurization slag modifier
The preparation method of the desulfurization residue modifier comprises the following steps: and ball-milling and uniformly mixing the soda powder, the lime powder and the fluorite powder according to the proportion by a ball-milling mixer to prepare the desulfurization residue modifier.
In some embodiments, the ball milling time and the ball milling speed of the ball mill can be controlled to obtain the desulfurization slag modifier with the required particle size.
According to the embodiment of the invention, the preparation method of the desulfurization slag modifier is simple in process, and the prepared desulfurization slag modifier material system is stable.
Molten iron desulphurization method
An embodiment of another aspect of the present invention provides a molten iron desulphurization method, including the following steps:
(1) adding the desulfurization slag modifier into a foundry ladle, and scraping front slag in the foundry ladle so as to enable the desulfurization modifier to fully react with the front slag;
(2) and stirring the molten iron in the ladle so as to fully desulfurize the molten iron.
In some embodiments, the slag modifier is added to the center of the ladle so that the slag modifier spreads over the surface of the molten iron.
In some embodiments, in order to allow the desulfurization slag modifier to sufficiently react with the molten iron pre-slag, the molten iron pre-slag after the addition of the desulfurization slag modifier is raked by the raking plate. And after the desulfurization slag modifier fully reacts with the slag before the molten iron, stirring and desulfurizing the stirring head at a normal speed.
In some embodiments, step (1) is preceded by slagging off the pre-slag in the ladle, and retaining 10-15 wt% of the pre-slag in the ladle.
According to the embodiment of the invention, generally speaking, 10-15 wt% of the front slag is reserved in the ladle, so that the time can be saved by 2-3 min, and the molten iron can be prevented from being cooled by 1-2 ℃. The higher temperature of the molten iron is beneficial to improving the efficiency of the subsequent desulfurization reaction, thereby improving the economic benefit.
In some embodiments, the time for raking the pre-slag in the step (1) is 20-30 s.
According to the embodiment of the invention, the pre-slag is raked for 20-30 s, so that the pre-slag is fully contacted and reacted with the desulfurization modifier, the transfer of sulfur elements to the pre-slag can be promoted, and the molten iron desulfurization efficiency is improved.
In some embodiments, the stirring time in step (2) is 9-10 min, and the stirring speed is 90-110 r/min.
According to the embodiment of the invention, the stirring head is stirred according to the stirring speed and the stirring time, so that the desulfurization residue modifier can fully react with molten iron, and the desulfurization efficiency is improved.
In some embodiments, after desulfurization, the consumption of the desulfurization residue modifier is 6-10 Kg/T relative to molten iron.
According to the embodiment of the invention, when the desulfurization slag modifier provided by the invention is used for desulfurizing molten iron, the consumption of the desulfurization slag modifier is low, and the method has a good industrial prospect.
In some embodiments, the amount of molten iron lost after desulfurization is 1.8 to 2.5%.
According to the embodiment of the invention, when the desulfurization slag modifier provided by the invention is used for desulfurizing molten iron, the loss amount of the molten iron is small, and the economic benefit is obvious.
Examples
Example 1
The raw material components of the desulfurization residue modifier comprise: 60-70 wt% of soda powder, 20-25 wt% of lime powder and 10-15 wt% of fluorite powder, wherein Na in the soda powder2CO3The weight percentage content of the component (A) is not less than 90 wt%; the weight percentage content of CaO in the lime powder is not less than 80 wt%; CaF in fluorite powder2The weight percentage of the component (A) is not less than 80 wt%.
Ball-milling the raw material components in the proportion in a ball mill, and uniformly mixing until the desulfurization residue modifier with the average particle size of not more than 1mm is obtained.
The desulfurization by using the desulfurization residue modifier comprises the following steps:
(1) reserving 10-15 wt% of front slag in a foundry ladle, adding the desulfurization slag modifier into the foundry ladle, and scraping the front slag in the foundry ladle for 20-30 s;
(2) and stirring the molten iron in the ladle by using a stirring head so as to fully desulfurize the molten iron.
The detection results show that: after the desulfurization is finished, the temperature of the molten iron in the ladle is reduced to 20 ℃; the desulfurization time is 12 min; the desulfurization rate is 91%; the loss of molten iron is 2.1 percent; the consumption of the desulfurization residue modifier is 7.5 Kg/T.
Example 2
The raw material components of the desulfurization residue modifier comprise: 60-70 wt% of soda powder, 15-20 wt% of lime powder and 10-15 wt% of fluorite powder, wherein Na in the soda powder2CO3The weight percentage content of the component (A) is not less than 90 wt%; the weight percentage content of CaO in the lime powder is not less than 80 wt%; CaF in fluorite powder2The weight percentage of the component (A) is not less than 80 wt%.
Ball-milling the raw material components in the proportion in a ball mill, and uniformly mixing until the desulfurization residue modifier with the average particle size of not more than 1mm is obtained.
The desulfurization by using the desulfurization residue modifier comprises the following steps:
(1) reserving 10-15 wt% of front slag in a foundry ladle, adding the desulfurization slag modifier into the foundry ladle, and scraping the front slag in the foundry ladle for 20-30 s;
(2) and stirring the molten iron in the ladle by using a stirring head so as to fully desulfurize the molten iron.
Detecting to obtain the product, and after the desulfurization is finished, reducing the temperature of the molten iron in the ladle to 25 ℃; the desulfurization time is 13 min; the desulfurization rate was 89%; the loss of molten iron is 2.5 percent; the consumption of the desulfurization residue modifier is 10.0 Kg/T.
Example 3
The raw material components of the desulfurization residue modifier comprise: 65-75 wt% of soda powder, 20-25 wt% of lime powder and 10-15 wt% of fluorite powder, wherein Na in the soda powder2CO3The weight percentage content of the component (A) is not less than 90 wt%; the weight percentage content of CaO in the lime powder is not less than 80 wt%; CaF in fluorite powder2The weight percentage of the components is not less than 80wt percent。
Ball-milling the raw material components in the proportion in a ball mill, and uniformly mixing until the desulfurization residue modifier with the average particle size of not more than 1mm is obtained.
The desulfurization by using the desulfurization residue modifier comprises the following steps:
(1) reserving 10-15 wt% of front slag in a foundry ladle, adding the desulfurization slag modifier into the foundry ladle, and scraping the front slag in the foundry ladle for 20-30 s;
(2) and stirring the molten iron in the ladle by using a stirring head so as to fully desulfurize the molten iron.
Detecting to obtain the product, and after the desulfurization is finished, reducing the temperature of the molten iron in the ladle to 16 ℃; the desulfurization time is 10 min; the desulfurization rate was 94%; the loss of molten iron is 1.8%; the consumption of the desulfurization residue modifier is 6.0 Kg/T.
Example 4
The raw material components of the desulfurization residue modifier comprise: 65-75 wt% of soda powder, 15-20 wt% of lime powder and 10-15 wt% of fluorite powder, wherein Na in the soda powder2CO3The weight percentage content of the component (A) is not less than 90 wt%; the weight percentage content of CaO in the lime powder is not less than 80 wt%; CaF in fluorite powder2The weight percentage of the component (A) is not less than 80 wt%.
Ball-milling the raw material components in the proportion in a ball mill, and uniformly mixing until the desulfurization residue modifier with the average particle size of not more than 1mm is obtained.
The desulfurization by using the desulfurization residue modifier comprises the following steps:
(1) reserving 10-15 wt% of front slag in a foundry ladle, adding the desulfurization slag modifier into the foundry ladle, and scraping the front slag in the foundry ladle for 20-30 s;
(2) and stirring the molten iron in the ladle by using a stirring head so as to fully desulfurize the molten iron.
Detecting to obtain that the temperature of the molten iron in the ladle is reduced to 22 ℃ after the desulfurization is finished; the desulfurization time is 12 min; the desulfurization rate is 90 percent; the loss of molten iron is 2.2%; the consumption of the desulfurization residue modifier is 8.5 Kg/T.
Therefore, the desulfurization slag modifier provided by the invention is utilizedWhen the desulphurization is carried out, the pre-slag does not need to be scraped completely, and 10-15 wt% of the pre-slag can be left for continuing the desulphurization operation, so that the slag-scraping time of the pre-slag is obviously reduced, and the problem of overlarge temperature drop of molten iron is avoided. The raw material components of the desulfurization residue modifier provided by the invention are matched and promoted with soda powder, lime powder and fluorite powder, and Na in desulfurization residue is increased2The content of O, the alkalinity of the slag, the viscosity of the slag and other comprehensive effects are improved, the capacity of sulfur elements in the slag is obviously improved, the molten iron desulphurization reaction of a slag-iron interface is promoted, and the desulphurization effect of a molten pool is improved. The desulfurization slag modifier has the advantages of low production cost, high desulfurization efficiency, low consumption of the desulfurization slag modifier and the like, effectively improves the economic benefit of iron and steel enterprises, and has good industrial application prospect.
While the present application has been described with reference to preferred embodiments, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the present application, and in particular, features shown in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims (10)

1. The desulfurization slag modifier is characterized by comprising the following raw material components in parts by weight based on 100 parts by weight:
Na2CO360-75 parts by weight of soda powder with the weight percentage not less than 90 wt%;
15-25 parts of lime powder with the weight percentage of CaO not less than 80 wt%;
CaF210-15 parts by weight of fluorite powder with the weight percentage content not less than 80 wt%.
2. The desulfurization slag modifier according to claim 1, wherein the desulfurization slag modifier is a powder mixture having an average particle diameter of not more than 1 mm.
3. The desulfurization slag modifier according to claim 1, wherein the S content in the lime powder and the fluorite powder is not higher than 0.1 wt%.
4. The desulfurization slag modifier according to claim 1, wherein the desulfurization degree of the desulfurization slag modifier is 89-94%.
5. A molten iron desulphurization method is characterized by comprising the following steps:
(1) adding the desulfurization slag modifier according to any one of claims 1 to 4 into a ladle, and raking the pre-slag in the ladle so as to enable the desulfurization modifier to fully react with the pre-slag;
(2) and stirring the molten iron in the ladle so as to fully desulfurize the molten iron.
6. The desulfurization method according to claim 5, wherein the step (1) is preceded by slagging off the pre-slag in the ladle, and 10-15 wt% of the pre-slag is retained in the ladle.
7. The desulfurization method according to claim 5, wherein the time for raking the pre-slag in the step (1) is 20-30 s.
8. The desulfurization method according to claim 5, wherein the stirring time in the step (2) is 9 to 10min, and the stirring speed is 90 to 110 r/min.
9. The desulfurization method according to claim 5, wherein after desulfurization, the consumption of the desulfurization residue modifier is 6 to 10Kg/T relative to molten iron.
10. The desulfurization method according to claim 5, wherein the loss amount of the molten iron after desulfurization is 1.8 to 2.5%.
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